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1347 Articles

We Ruined Status LEDs; Here’s Why That Needs To Change

February 20, 2020 by 259 Comments

Ah, the humble status LED. Just about every piece of home electronics, every circuit module, and anything else that draws current seems to have one. In the days of yore, a humble indicator gave a subtle glow from behind a panel, and this was fine. Then the 1990s happened, and everything got much much worse.

It’s Not The Technology, It’s How You Use It

With great brightness, comes great responsibility.

The 1990s brought us much good: Nirvana, Linux, and of course the blue LED. Much like “Teen Spirit”, the latter quickly fell into overuse: the technology rapidly became the sigil of all that was new and great, much to the ocular pain of the buying public.

This decision ranks up there for stupidity with other such questionable choices as hiring a rental car at the airport, or invading Russia in the winter. A status LED, most would agree, is there to indicate status. It need only deliver enough light to be seen when observed by a querying eye. What it need not do is glow with the intensity of a dying star, or illuminate an entire room for that matter. But, in the desperate attempts of product designers to appear on the cutting edge, the new, brighter LED triumphed over all in these applications. Continue reading “We Ruined Status LEDs; Here’s Why That Needs To Change” →

How Many LEDs Can You Drive?

February 18, 2020 by 35 Comments

Driving more than a handful of LEDs from a microcontroller is often a feat that takes tedious wiring, tricking the processor, or a lot of extra external hardware. Charlieplexing is perhaps the most notorious of these methods, and checks two of those three boxes. This library for the Teensy 4.0 checks all three, but it can also drive a truly staggering 32,000 LEDs at one time.

The TriantaduoWS2811 library is able to drive 32 channels of LEDs from a Teensy 4.0 using only three pins and minimal processor resources. It uses the FlexIO and DMA subsystems of the i.MX RT1062, the particular ARM processor on the Teensy, to drive four external shift registers. Together, the system is able to achieve 30 frames per second on with 1,000 LEDs per channel, for a total of 32,000 LEDs. Whoah.

[Ward] aka [wramsdell] wondered what one would do with all of the horsepower of a Teensy microcontroller when he first saw its specifications, and was able to build this project to take advantage of its features. What’s surprising, though, is that it doesn’t use nearly everything the processor is capable of, so you can do other tasks at the same time as driving that giant LED display.

Have LED Bulbs Reached Their Final (and Cheapest) Form?

February 16, 2020 by 129 Comments

[electronupdate] has done a lot of LED light bulb teardowns over the years, witnessing a drive towards ever-cheaper and ever-simpler implementations, and suspects that LED light bulb design has finally reached its ultimate goal. This teardown of a recent dollar store example shows that cost-cutting has managed to shave even more off what was already looking like a market saturated with bottom-dollar design.

The electrical components inside this glowing model of cost-cutting consists of one PCB (previously-seen dollar store LED bulb examples had two), eleven LEDs, one bridge rectifier, two resistors, and a controller IC. A wirewound resistor apparently also serves as a fuse, just in case.

Inside the unmarked controller IC. The design is as cheap as it is clever in its cost-cutting.

That’s not all. [electronupdate] goes beyond a simple teardown and has decapped the controller IC to see what lurks inside, and the result is shown here. This controller is responsible for driving the LEDs from the ~100 Volts DC that the bridge rectifier and large electrolytic cap present to it, and it’s both cheap and clever in its own way.

The top half is a big transistor for chopping the voltage and the bottom half is the simple control logic; operation is fast enough that no flicker is perceived in the LEDs, and no output smoothing cap is needed. The result, of course, is fewer components and lower cost.

Some of you may recall that back in the early days of LED lighting, bulbs that could last 100,000 hours were a hot promise. That didn’t happen for a variety of reasons and the march towards being an everyday consumable where cost was paramount continued. [electronupdate] feels they have probably reached that ultimate goal, at least until something else changes. They work, they’re cheap, and just about everything else has been successfully pried up and tossed out the door.

HackIt: Why Aren’t We Hacking On The LED Printer?

February 11, 2020 by 54 Comments

Strings of LEDs are a staple of the type of project we see here at Hackaday, with addressable devices such as the WS2812 in particular having changed beyond recognition what is possible on a reasonable budget. They’ve appeared in all kinds of projects, but are perhaps most memorable when used in imaging projects such as screen-like arrays or persistence-of-vision systems. There’s another addressable LED product that we haven’t seen here, which is quite a surprise considering that it can be found with relative ease in junk piles and has been on the market for decades. We’re talking about the LED printer, and the addressable LED product in question is a very high density array of LEDs the width of a page, designed to place an image of the page to be printed on the toner transfer drum.

Continue reading “HackIt: Why Aren’t We Hacking On The LED Printer?” →

Flicker Detector Lets You Hear What You Can’t See

January 28, 2020 by 58 Comments

Have you ever looked at modern LED lighting and noticed, perhaps on the very edge of your perception, that they seemed to be flickering? Well, that’s because they probably are. As are the LEDs in your computer monitor, or your phone’s screen. Pulse width modulation (PWM) is used extensively with LEDs to provide brightness control, and if it’s not done well, it can lead to headaches and eyestrain.

Looking to quantify just how much flashing light we’re being exposed to, [Faransky] has created a simple little gadget that essentially converts flashing light into an audio tone the human ear can pick up. Those LEDs might be blinking on and off fast enough to fool our eyes, but your ears can hear frequencies much higher than those used in common PWM solutions. In the video after the break, you can see what various LED light sources sound like when using the device.

The electronics here are exceptionally simple. Just connect a small solar panel to an audio amplifier, in this case the PAM8403, and listen to the output. To make it a bit more convenient to use, there’s an internal battery, charger circuit and USB-C port; but you could just as easily run the thing off of a 9 V alkaline if you wanted to build one from what’s already in the parts bin.

Who knows? If you carry this thing around long enough, you might even hear the far less common binary code modulation in action (but probably not).

Continue reading “Flicker Detector Lets You Hear What You Can’t See” →

New Part Day: SK6812 Mini-E. A Hand Solderable Neopixel Compatible LED!

January 28, 2020 by 23 Comments

Normally when we give you a New Part Day piece, it concerns a component that you will have never seen before. The subject of this find by [Robert Fitzsimons] then is a slight departure from that norm, given that the SK6812 Mini-E is a WS2812 or Neopixel compatible multi-colour LED of a type that has been available for a while now.

What makes this component new though is its packaging. The Mini-E variant of the SK6812 only appeared last year and has now found its way through to smaller order quantities on AliExpress. Its special feature is that it has a set of flat leads rather than the usual pads on the underside of the package. This means that unlike its predecessors it is readily hand solderable, as he demonstrates by attaching a set of leads to one.

The leads emerge halfway up the side of the device, which seems designed to be mounted recessed within a PCB hole. He demonstrates this with a piece of stripboard, and remarks that they would make a good choice for many small projects such as Shitty Add-On boards.

We’ve touched the leadless SK6812s a few times before, along the way remarking that in some respects they are better than the WS2812 they follow.

Continue reading “New Part Day: SK6812 Mini-E. A Hand Solderable Neopixel Compatible LED!” →

It’s An LED Cube, But Maybe Not Quite What You Were Expecting

January 27, 2020 by 11 Comments

LED cubes are a pleasing ornament and still something of a talking point, but now they have reached the point of being available as inexpensive kits from China. The simpler ones don’t have quite the cachet they used to. It’s still a project that can deliver a few surprises though, as [Moritz v. Sivers] shows us very well with his glass LED cube. Instead of the usual wire frame construction he’s employed a novel technique of applying each layer of WS2812 LEDs to its own glass PCB.

The PCBs are created with self-adhesive copper foil, cut out with a CNC cutter and painstakingly transferred to the glass substrate with the help of a piece of transfer paper. The LEDs are soldered on, and once each board has been tested they are mounted in the manner of a toast rack to laser cut acrylic corner pieces. There are four layers of 16 LEDs each, which might not make for the largest cube, but still makes for a respectable show. The addressable LEDs take it a level above the 3D matrix type of cube with which you might already be familiar, and the extra time required to load each value into them doesn’t seem to slow the display down.

There are a couple of videos we’ve placed below the break, one showing it in action and the other taking us through the build process. This last one should provide plenty of inspiration for anyone with an interest in creating this type of PCB on glass or any other unusual substrate. Continue reading “It’s An LED Cube, But Maybe Not Quite What You Were Expecting” →